The present invention relates to an air conditioning apparatus for a vehicle, in which air passes through a cooling heat exchanger upwardly from below.
In a conventional air conditioning apparatus for a vehicle described in JP-A-9-123748, an evaporator (cooling heat exchanger) 21 is disposed approximately horizontally and air flows through the evaporator 21 upwardly from a lower side thereof, to reduce a size of an air conditioning unit 2.
Referring now to FIGS. 6A and 6B, in the conventional apparatus, to improve draining performance of condensed water in the evaporator 21, the evaporator 21 is disposed to be inclined from a horizontal direction by a small angle xcex8, a flow direction A of air blown by a blower (not shown) toward the lower side of the evaporator 21 is set to a vehicle width direction similarly to an inclination direction of the evaporator 21 and a tube longitudinal direction B of the evaporator 21.
That is, the evaporator 21 is disposed to be inclined downwardly toward a flow forward side of air blown toward the lower side of the evaporator 21, and the longitudinal direction B of tubes 21a forming refrigerant passages in the evaporator 21 extends to the same direction as the flow direction A of blown-air.
Thus, condensed water generated in the evaporator 21 moves on a surface of the tubes 21a toward an inclination lower end portion C of the evaporator 21, due to gravity of condensed water and pressure of blown-air. Condensed water D is collected to the inclination lower end portion C of the evaporator 21, and falls downwardly from the inclination lower end portion C.
However, as a result of an experiment and a study by the inventors of the present invention, the draining performance of condensed water from the evaporator 21 is deteriorated from the following reason.
That is, according to the conventional apparatus, the condensed water D is collected in the inclination lower end portion C of the evaporator 21, and the inclination lower end portion C of the evaporator 21 is placed at an extending inner end of the flow direction A of blown-air. Therefore, main flow (i.e., the air flow having a high air-flow velocity) of blown-air is toward the inclination lower end portion C of the evaporator 21. As a result, a high pressure area E due to main flow of blown-air is formed around the inclination lower end portion C.
Thus, condensed water does not fall and stays between fins 21b by a balance between the gravity of condensed water and air pressure for pushing the condensed water. Further, when the air pressure applied to the condensed water is larger than the gravity of condensed water by a high velocity (Hi) operation of the blower, condensed water may be scattered toward a downstream air side (upper side) of the evaporator 21.
Thus, the draining performance of condensed water is deteriorated as described above. As a result, water contained in air blown into a passenger compartment is increased, and a windshield of the vehicle may be fogged.
In light of the above-described problem, it is an object of the present invention to improve draining performance of condensed water of a cooling heat exchanger, in an air conditioning apparatus for a vehicle where air upwardly passes through the cooling heat exchanger from below.
To achieve the above-described object, in the present invention, a cooling heat exchanger (21) is inclined in the same direction as a longitudinal direction (B) of tubes (21a) of the cooling heat exchanger (21), and the cooling heat exchanger (21) is disposed so that a flow direction (A) of air flowing into a lower side of the cooling heat exchanger (21) is perpendicular to the longitudinal direction (B) of the tubes (21a).
Because the longitudinal direction (B) of the tubes (21a) of the cooling heat exchanger (21) corresponds to the inclination direction of the cooling heat exchanger (21), condensed water generated in the cooling heat exchanger (21) moves along tube surfaces in the longitudinal direction (B) toward an inclination lower end portion (C) of the cooling heat exchanger (21) by gravity of condensed water, and condensed water (D) is collected to the inclination lower end portion (C).
On the other hand, because main flow air (i.e., air having a high flow velocity) blown toward the lower side of the cooling heat exchanger (21) flows into a most inner position within the case (20), a high pressure area (E) due to the main flow air is formed at the most inner position on the lower side of the cooling heat exchanger (21).
At this time, because a flow direction (A) of air flowing toward a lower side of the cooling heat exchanger (21) is perpendicular to the longitudinal direction (B) of the tubes (21a), the inclination lower end portion (C) of the cooling heat exchanger (21) extends in parallel with the flow direction (A) of air, as shown in FIG. 5B. Therefore, the inclination lower end portion (C) of the cooling heat exchanger (21) corresponds (overlaps) to the high pressure area (E) at a very small part, and almost all of the inclination lower end portion (C) is positioned to be shifted from the high pressure area (E).
Therefore, almost all of the condensed water (D) staying in the inclination lower end portion (C) can fall smoothly downwardly without being pushed by air pressure in the high pressure area (E). As a result, even in the air conditioning apparatus for a vehicle where air passes through the cooling heat exchanger (21) from below upwardly, the draining performance of condensed water can be greatly improved.
In the present invention, the flow direction (A) of air blown toward the lower side of the cooling heat exchanger (21) is in a vehicle width direction, and the longitudinal direction (B) of the tubes (21a) is a vehicle front-rear direction. Therefore, even in a case where the air conditioning apparatus is disposed in a small space of an instrument panel at a front side of a passenger compartment, the perpendicular relation between the flow direction (A) of air and the longitudinal direction (B) of the tubes (21a) can be readily obtained.
Further, in the present invention, the air conditioning apparatus includes a blower unit (1) for blowing air, and an air conditioning unit (2) for adjusting temperature of air blown into the passenger compartment of the vehicle from the blower unit (1). In the air conditioning apparatus, the cooling heat exchanger (21) of the air conditioning unit (2) is disposed to be inclined from a horizontal direction by a small angle (xcex8) so that air is introduced into the cooling heat exchanger (21) from below and flows upwardly, the cooling heat exchanger (21) is inclined in the same direction as the longitudinal direction (B) of the tubes (21a), and the cooling heat exchanger (21) is disposed so that the longitudinal direction (B) of the tubes (21a) is in the vehicle front-rear direction and the flow direction (A) of air blown from the blower unit (1) into the lower side of the cooling heat exchanger (21) is in the vehicle width direction.
Thus, in the air conditioning apparatus having the blower unit (1) and the air conditioning unit (2), the flow direction (A) of air blown toward the lower side of the cooling heat exchanger (21) is in the vehicle width direction, and the longitudinal direction (B) of the tubes (21a) is in the vehicle front-rear direction. Accordingly, the perpendicular relation between the flow direction (A) of air and the longitudinal direction (B) of tubes (21a) can be obtained. As a result, the draining performance of condensed water can be improved. Further, even when the air conditioning apparatus is disposed in a small space of the instrument panel at a front portion of the passenger compartment, the above-described perpendicular relation can be sufficiently proposed.
In the present invention, the blower unit (1) can be disposed to be shifted to a front passenger""s seat side in a front portion of the passenger compartment, and the air conditioning unit (2) can be disposed at a center portion in the front portion of the passenger compartment.
Further, in the present invention, the cooling heat exchanger (21) is disposed to be inclined so that a vehicle front side of the cooling heat exchanger (21) becomes higher and a vehicle rear side thereof becomes lower. Therefore, an interference between the bottom of the case (20) and a vehicle floor which is higher at the vehicle front side can be readily prevented. Further, since the cooling heat exchanger (21) is inclined, an operation space of the air-mixing door (24) can be readily obtained.
Further, in the present invention, a heating heat exchanger (22) for heating air is approximately horizontally disposed on an upper side of the cooling heat exchanger (21) at a vehicle front side so that a bypass passage (23) through which air bypasses the heating heat exchanger (22) is formed at a vehicle rear side of the heating heat exchanger (22). An air mixing door (24) for adjusting a ratio between an amount of air passing through the heating heat exchanger (22) and an amount of air passing through the bypass passage (23) is disposed between the cooling heat exchanger (21) and the heating heat exchanger (22). Further, a face opening portion (28) for blowing air toward an upper side of the passenger compartment is provided on an upper portion of the case (20) at a position of a vehicle rear side.
Thus, within the case (20), an air passage from a downstream air side of the cooling heat exchanger (21) to the face opening portion (28) at the vehicle rear side through the bypass passage at the vehicle rear side can be formed straightly, thereby reducing air flow resistance during a face mode.
In the present invention, the term of xe2x80x9cperpendicularxe2x80x9d is not limited to the relation where the flow direction (A) of air is crossed with the longitudinal direction (B) of the tubes (21a) by the just 90xc2x0 angle, but includes the relation where the flow direction (A) of air is crossed with the longitudinal direction (B) of the tubes (21a) by an angle approximately equal to 90xc2x0. Similarly, the term of xe2x80x9chorizontallyxe2x80x9d is not limited to the just horizontal direction, but includes an arrangement approximately horizontally.